1. Field
One embodiment of the invention relates to an information recording apparatus that carries out write and readout of information with respect to, for example, a disc-shaped storage medium with a large capacity, such as a hard disc, by using a semiconductor memory as a cache, and also relates to a control method of the information recording apparatus.
2. Description of the Related Art
As is well-known, a hard disc is a large-capacity and reliable information recording medium, and is widespread in many areas, for example, to be used for recording computer data, image data, audio data, and so on in recent years. In addition, the size of the hard disc has been downsized to make it mountable in a portable electronic device.
For the above reason, when downsizing an information recording apparatus that includes such hard disc, a semiconductor memory capable of high-speed write and high-speed readout of information is used as a cache memory for the hard disc, thereby increasing the speed required for write and readout of the information.
That is, the information recording apparatus of this kind carries out write and readout of information with respect to an external host device via the cache memory, and carries out transfer of information between the hard disc and the cache memory. In this manner, write and readout of information as seen from the outside is speeded up.
At present, it is considered to attempt to save battery energy by reducing the number of drives of the hard disc, that is, the number of writes and readouts of information with respect to the hard disc, in a manner that a non-volatile memory is included as a cache with respect to the hard disc in addition to the cache memory. Such an information recording apparatus is called an NV (non volatile)-cache compatible HDD (hard disc drive), and is standardized.
In the information recording apparatus including a hard disc as the information recording medium, in a case where a defect occurs in a specific region (sector) on the hard disc and the reliability of write and readout of information is extremely lowered, a substitution processing for substituting the defect region with another region on the hard disc is carried out.
However, in such a substitution processing, a magnetic head needs to be moved to a substituting region corresponding to the defect region when write and readout of information is carried out with respect to the hard disc. Therefore, additional time is required for such move in the write and readout of information.
Jpn. Pat. Appln. Publication No. 2-109151 discloses a configuration where, when data written in a battery backup RAM (random access memory) is written in a disc, a region in the RAM in which the data was failed to be written in the disc is stored is configured to be a substituting region, in a period where there is no request for write and readout from a host computer.